From Book X of the Republic: 42. And now since we have reverted to the subject of poetry, let this our defense serve to show the reasonableness of our former judgment in sending away out of our State an art having the tendencies which we have described; for reason constrained us. But that she may impute to us any harshness or want of politeness, let us tell her that there is an ancient quarrel between philosophy and poetry; of which there are many proofs, such as the saying of 'the yelping hound howling at her lord,' or of one 'mighty in the vain talk of fools,' and 'the mob of sages circumventing Zeus,' and the 'subtle thinkers who are beggars after all'; and there are innumerable other signs of ancient enmity between them.
In Plato's ideal state, lyric poetry-- which is the product not of reason and logic, but of inspiration and emotion--shall be banned. This section is often criticized and attacked as an early example of state censorship; it also demonstrates, however, that the greeks perceived a clear distinction between the aesthetic and logical approaches to "truth".
Without getting longwinded or too theoretical, I think this distinction--as well as the argument for banning or controlling artistic and poetic creation--still holds. The latest brain fart spewed on some bubblegum star or rapper's CD is not near to Newtonian (or Einsteinian) constants, nor even to a syllogism. Poetry and really literature as a whole are anecdotally true at best and not on the same level as physical or mathematical laws. Literature may have psychological and occasionally historical relevance, yet it is not proof of any psychological theory or concept or the historical record itself. It's qualitative, not quantitative. Most students know far more about Hamlet, an imaginary "construct," than they do about English (or Danish) history of the 16th century, and Shakespeare's abiding presence ( really somewhat sinister) demonstrates how the literary myth overpowers the historical and economic reality of the Tudorian monarchy. Shakespeare's play Hamlet is, however rhetorically marvelous, not the historical record, nor does it contain any necessarily true statements regarding politics, psychology, or the physical world. Entertainment, much lower than classic poetry, is far less concerned with/addressed to any sort of logical or scientific truth.
Though many so-called liberals protest any forms of censorship, there may be decent grounds for the Chinese authorities controlling the spread of discos and pop culture in their country; and though a complete banning of western entertainment in the islamic countries may seem wrong--it is--controlling the spread of the religion of celebrity and instant gratifcation may not be the worst thing a country can do. Citizens in Morocco or China or Saudi Arabia should be able to read Shelley or Hemingway, listen to Bartok or Ellington or Metheny, I think, but do they need to have their kids listening to gangsta rap and Britanny Spears and death metal or reading Hustler? I think not. But the danger is letting religious zealots be the Ministers of Information, instead of Platos.